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SCADA Systems: Secure or Compliant?

Magmeter Basics

DAQ Gets on Track

Is APC Just Shelfware?

On the Web

Andrew Bond’s European Process News

Is your operator training simulator faithful

to your plant? High-mid- and low-fi delity

modeling each have their place.

Getting Real

issing project milestones was not an option. Never mind that His Royal Highness The Duke of York would be visiting at start-up; process expansions and control-room up-

dates were a critical piece of a £390-million “Project Gen-esis” modernization program to turn Ineos ChlorVinyls’ (www.ineoschlor.com) Runcorn, Cheshire, U.K., site into a showpiece of eco-friendly chemical processing. However, with a year to go, process control manager Philip Masding couldn’t � nd a supplier who could model his plant in time to test how his control scheme would handle his process and cope with dynamic process disturbances. It’s a harder to � nd experts in chlor-alkali process modeling than more com-mon petrochemical modeling.

“We looked at a number of possible suppliers, and their delivery dates were always going to be short of time,” says Masding. Knowing time was short no matter who did the work, he took the work in-house, linking his control system to models he built himself. “We started with the most criti-cal areas, and we would at least train operators on the most critical areas of the plant,” using a general-purpose simu-lator to model, test and ultimately train operators, starting with gas pressure controls.

Masding didn’t rest on his laurels. He has since “drasti-

cally reduced the num-ber of large-scale excur-sions [or disturbances] that we’ve had by applying the model to the control scheme,” using updated op-erating data.

Dynamic models that feed simulated process data to of-� ine test versions of control systems have become an indis-pensable tool for process control engineers. The term for them, op-erator training simulators (OTS), is a bit of a misnomer because these sys-tems address ongoing needs, from con-trol system factory acceptance testing (FAT) through start-up and ongoing training and sys-tem improvements. While lower levels of � delity, or detail, characterize most OTS systems, high-� delity sys-tems are still mainly used for new process designs. As those high-end simulators, once relegated to steady-state engineer-ing designs, add dynamic modeling, the costs and bene� ts of such systems are as varied as a plant’s needs.

Testing, Training Bene� ts Martin Berutti, business director of Mynah Technologies (www.mynah.com), says OTS bene� ts include reduced “operations-induced unscheduled downtime,” faster time to market for control systems, product quality, operating

costs and mitigation of risk. He cites savings from $100,000 to $500,000 per day when OTS speeds commissioning and

validation; $500,000 to $1 million per production run based on extensive software testing to reduce off-spec product; and

$500,000 to $100,000 per hour through better-trained operations staff and reduced automation system errors for cost-avoidance of

$50,000 to $1 million per incident.“The cost of running a full series of tests on-site with live equipment

are considerable, versus the cost of running a full series of multiple tests, multiple times, with multiple scenarios in the back of our of� ce,” agrees

Andrew Robinson, project engineer with control systems integration � rm Avid Solutions (www.avidsolutionsinc.com) in Apex, N.C. Avid works at several phar-maceutical plants where FDA validation is stringent. He cites a recent job where one engineer spent two weeks in a plant starting up a batch-process DCS. With-out thorough off-site testing, he says the start-up “would have probably taken two or three times as long and two or maybe three people to get the job done right.”

DCS vendors use OTS on their own staging � oors before shipping a system, which lets them test and update the customer’s con� guration to “save weeks or months of DCS commissioning time,” says Tobias Scheele, vice president of ad-

vanced applications for Invensys Process Systems (www.ips.invensys.com). This reduces con� guration errors in the � eld. He adds that the value to the plant depends on “the revenue associated with the additional days of early production, which usually dwarfs the cost of the control checkout effort.”

Systems can be updated daily on a DCS vendor’s stag-ing � oor. Con� guration bugs found in the morning will be � xed in the afternoon, and the process repeats many times. Once the system is shipped, the plant’s personnel will then run through their own checkout, testing the physical, on-line system as they follow with start-up and commissioning. However, training strategies must start before that because the need is critical—and expensive. OTS systems address the critical need for training as soon as models and the DCS con� guration can be simulated or “emulated.”

You Decide on CostsSoftware costs can run thousands of dollars up to several million dollars; Invensys’ largest OTS had more than 80,000 I/O points. And there’s more to a system than process mod-els. The control system needs to offer its own simulation or emulation function, to which the customer’s control con� g-uration and graphics must be added.

A full solution also includes training courseware and a training curriculum. Such a system can cost $135,000 at the low end, says Mark O’Rosky, OTS operator training solu-tions group leader at Emerson Process Management (www.emersonprocess.com). He adds that Emerson’s entry-level OTS Express occupies a sweet spot for his OTS customers in the $250,000 to $450,000 range, which covers an applica-tion “about the size of a hydro-treating unit or a crude unit at a re� nery, typically a one-process unit with two operator training seats.”

O’Rosky explains that costs vary be-cause needs vary. Sometimes the models are extensive and the training application requires only a single seat. Other times, the models may need to cover only a few critical vessels, but the training applica-tion may require that the instructor man-age nine seats and invoke nine different failures at the same time.

Even the organizational chart—the trainer’s area of responsibility—can in part determine the scope, or phasing, of OTS modules. “The training curricu-lum could be composed of 15 critical process operations,” says Pete Henderson, product marketing manager, Honey-well Process Solutions (www.honeywell.com/ps). “Other customers may choose to integrate multiple models into blocks, so that interactions between operation teams can be seen, and the impact to their peers as a consequence of their performance can be managed.”

Users can buy models à la carte or as an option in a DCS contract. Cape Software’s (www.capesoftware.com) VP Link is offered as a stand-alone modeler or as an option in many leading DCS systems. Yokogawa Corp. of America (www.us.yokogawa.com), for one, offers it as a small-scale testing option in its Centum VP, while also offering a high-� delity solution from Omega Simulation (www.omegasim.co.jp), which can cost into the millions of dollars—it just depends on the scope of the plant’s project, control system and training needs.

Working in a recent oil and gas project, Winston Jenks, Cape’s technical director and CEO, says the higher-end Omega system was needed for its more detailed models and a higher-bandwidth interface because “there were so many tags to move back and forth on that system, we needed this sort of high-performance I/O interface.”

A 2005 quote credited to John Payne, BP operations

technical training manager for the Western Hemi-

sphere, raises concerns that a ticking “demographic

time bomb” is threatening to compromise the ability of

plants to � nd skilled operations personnel.

“The average age of workers in the energy indus-

try is now over 50, and the industry estimates that

up to half its current workforce, more than 500,000

workers, will retire within � ve to 10 years,” said Em-

ily Stover Derocco, assistant secretary with the U.S.

Department of Labor’s

Employment and Train-

ing Administration, to the

U.S. Senate Committee

on Energy and Natural

Resources in 2007.

Citing a paucity of skills

among retirees’ entry-

level replacements, she

called for “creative solu-

tions to help new workers

gain necessary skills as

quickly as possible,” and OTS � ts the bill for process

control training.

Even with a recession and layoffs afoot, many pro-

cess industries are scratching to � nd good recruits.

Even in oil-related sectors where capital projects may

have been planned four years ago when oil was cheap

(as it is again), and layoffs are low to keep up with de-

mand, skilled operators are always at a premium.

trainer’s area of responsibility—can in part determine the

Department of Labor’s

Employment and Train-

ing Administration, to the

U.S. Senate Committee

on Energy and Natural

Resources in 2007.

among retirees’ entry-

level replacements, she

called for “creative solu-

tions to help new workers

gain necessary skills as

quickly as possible,” and OTS � ts the bill for process

Most process control engineers � nd that DCS suppliers’

simulation/emulation features provide a perfect, realistic

human-machine interface (HMI) for control system trainees.

After all, the offline DCS training system is identical to the

online system running the process, albeit with simulated I/O.

It can’t get any “realer” than that. Or can it? Recent develop-

ments in 3D modeling and virtual reality are now pushing the

boundaries of simulation HMI.

In February, Invensys Process Systems

(www.ips.invensys.com) announced a new

3D “Immersive Virtual Reality” human-

machine interface, complete with headset,

for use by “not only control room opera-

tors, but also outside operators,” says To-

bias Scheele, Invensys’ vice president of

advanced applications. Scheduled for re-

lease this year, the system is being used at

plants now, including multiple global com-

panies.

Scheele says it will include dynamic models “that are on-

line and run in parallel to the actual plant,” which entails a

real-time database connection. The technology is “an exten-

sion of process simulation, and DCS modeling is the key for

total team training—control room and � eld—and safety anal-

ysis,” adds Maurizio Rovaglio, Invensys’ vice president.

While the concept seems bleeding edge, 3D modeling—

without the goggles—has proven “extremely bene� cial for

the control engineer to visualize how a system is operating,”

says Brent Stromwall, vice president for control systems in-

tegrator Polytron (www.polytron.com), Duluth, Ga. He also

claims 50% reductions in control system start-up time.

He adds the technology “easily reduces” project start-up

costs by 50%. Polytron has used 3D models for complex,

full-plant dynamics, as well as more basic challenges, such

as � ow restrictions in pipes and the interaction of bottles

as they move from a wide, collect-

ing conveyor to a narrow, down-

stream line in a bottling plant. He

cites Demo3D from Emulate 3D

(www.demo3d.com) as a useful

tool with underyling physics mod-

els he calls “the next big thing.”

In addition to system testing,

Stromwall says the same model

used for designing lines also “pro-

duces tremendous bene� ts for

training by giving operators the visuals they need when op-

erating or interacting with the control system.”

The 3D simulations make learning more “tactile” and

“hands-on” when applications are hard to visualize, says

George Zhookoff, product manager for E2M, Polytron’s sys-

tem analytics partner. He adds that trainees “ages 10 to 50”

can bene� t, but “the younger generation tends to have more

of a more of a comfort level in the beginning.”

More OPC NeededAn entire OTS system can reside in one high-end PC or, more commonly, two or more boxes that are interfaced us-ing proprietary interfaces, or via OPC. At Ineos’ Runcorn facility (above), Masding chose OPC to send models he built in VisSim, whose U.S. supplier is Visual Solutions (www.vissol.com), to his DCS (Emerson’s Delta V). In a pi-lot study, he fed physical 4-20mA outputs from the control system to an analog-to-digital card on the PC running the model, but that was for � ve loops. It would be “very dif� cult indeed” to do that on a full system with hundreds of I/O points, he says.

Not all vendors offer enough proprietary interfaces, and OPC isn’t ubiquitous. “Our wish is that every control sys-tem vendor would make an off-line control system simula-tor with open OPC data access,” says Berutti.

The lack of OPC may stem from a “mindset” issue, adds Cape’s Jenks, because “people usually think of OPC as a way to read data from the control system, and we’re more often writing data to it.” However, more OPC would of-fer users much greater � exibility, especially when they want more detailed models, including models for ancillary sub-processes, such as skid-mounted compressors with their own programmable controls. For example, operators may

need to know more than the on/off sta-tus of a compressor; they may need to know the operation of its staged opera-tion and status of components, such as lubrication-oil pumps, fuel-gas lines, turbines and motors.

Jenks believes the outlook is good for more and better interfaces beyond the DCS as more users demand them. He sees DCS vendors’ integrated safety and emergency shutdown systems as a leading indicator of things to come.

Semper Fidelis?The characteristic of � delity in depict-ing the online system is a contested criterion. The closest thing to a yard-stick for � delity is the ANSI/ISA 77.2 standard, titled “Fossil Fuel Power Plant Simulators: Functional Require-ments.” It doesn’t tell developers or us-ers how to achieve or evaluate various levels of � delity.

The standard’s Section 6.1 says sim-ulated instrument values in a “steady-state, full-power operation” simulation should be within 2% of the reference plant. However, Section 6.2 says tran-sient operations, as in dynamic OTS, require accuracy within 20%.

Should that 20% raise eyebrows? No, say the experts, including Masding,

whose experience gives him “a fair idea when the accuracy of a simulation is good enough.” His trainees will “get a fair-enough idea of how things are go-ing to react” if a simulated tank � lls in four instead of � ve minutes. In tweak-ing his control scheme, he doesn’t run equipment “within 20% of the burst-ing point.” Instead, he simulates distur-bances, compares simulated responses with the real-time system and makes incremental improvements when a “slightly different control scheme is better than the one we’ve got. I’m not expecting to be within 1% or 2%.”

High-� delity dynamic simulators can achieve single-digit accuracy that may be needed in a highly complex, continuous hydrocarbon process as opposed to a typical batch plant, and that appears to open a market for high-� delity dynamic simulation. Invensys’ Scheele says these can be used across the board for plant design, control sys-tem testing and operator training.

While noting that highly integrated and complex systems “tend to grow in cost,” Sheele adds. “The lowest lifecycle cost is usually the development of a high-� delity model during the design phase of a project that evolves into a high-� delity operator training simulator.”

Mynah’s Berutti counters that, “The biggest misconception in the industry is that simulation models developed for process design have applicability for operator training or control system test-ing,” because dynamic process design models rarely account for “the range of conditions and real-time performance necessary for operator training or con-trol system testing. The user would be best served by forgetting about this pipe dream and incorporating simulation for control system testing and training as an integral part of the automation project and control system lifecycle.”

The only resolution to this issue is found on the documentation of user needs and consultation with experts during the election process on a case-by-case basis. While no hard-and-fast rule can apply to all plants, it’s clear that simulation has become a critical component of control system testing and operator training

Bob Sperber is a contributing editor to Control.

Mynah’s Berutti counters that, “The

Reprinted with permission from Control Magazine, April 2009. On the Web at www.controlglobal.com.© PUTMAN. All Rights Reserved. Foster Printing Service: 866-879-9144, www.marketingreprints.com.

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